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V.—On the included Pebbles of the Upper Neocomian Sands of the South-East of England, especially those of the Upware and Potton Pebble Beds1

Published online by Cambridge University Press:  01 May 2009

Walter Keeping
Walter Keeping
Affiliation:
Lecturer on Geology in the University of Cambridge.
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Extract

It has often appeared to me that in working out the ancient physical features of the earth in former periods of its history, too little attention has been given to one simple set of evidences which are of wide-spread occurrence, and, frequently, of very clear and decided meaning. I refer to the included rock-fragments of conglomeratic deposits. An appeal to these fragments would, I believe, often bring out clearly-written facts of no small value for the elucidation of the nature of ancient sea-margins, as compared with the much-involved palæontological evidences with which we are made so much more familiar.

Type
Original Articles
Information
Geological Magazine , Volume 7 , Issue 9 , September 1880 , pp. 414 - 421
Copyright
Copyright © Cambridge University Press 1880

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References

page 415 note 1 This rock, and its fossils, are described more fully in another work on “The Fossils and Palæontological Affinities of the Neocomian Deposits of Upware and Brickhill,” not yet published.

page 417 note 1 Jurassic chert occurs in England in the Purbeck and Portland beds of Wiltshire and the Isle of Portland. Mr. E. B. Tawney tells me of beds of chert in the Lower Lias of Glamorganshire; and in the North of England Mr. J. F. Walker, of Sidney College, kindly refers me to such deposits in the Coralline Oolite near Malton.

page 418 note 1 Geol. Assoc. Report, Dec. 4, 1868.

page 419 note 1 See Blake on the Portlandian rocks of England, read before the Geological Society, January, 1880.

page 419 note 2 It is indeed remarkable that in the New Red Sandstones we know of no such accumulations of chert pebbles, derived from the Mountain Limestone, to correspond with the abundant flint pebble and gravel beds of Tertiary and modern times. There must surely be some such deposits somewhere hidden in the New Red.

page 420 note 1 In earlier Cretaceous times (Lower Neocomian) the two seas could have communicated only by their common union with the Atlantic in the west.

page 420 note 2 Mem. Geol. Suryey, vol. iv. p. 498.Google Scholar

page 421 note 1 Popular Science Review, 1879, vol. iii. p. 293.Google Scholar

page 421 note 2 Mr. J. J. Harris Teall suggested, in 1875, that the Lydian stone came from Palæozoic rocks to the east.—Sedgwick Prize Essay, 1875, p. 38.